The present invention relates generally to data communications. More particularly, the present invention relates to quality of service for stackable network switches.
The rapidly increasing popularity of networks such as the Internet has spurred the development of network services such as streaming audio and streaming video. These new services have different latency requirements than conventional network services such as electronic mail and file transfer. New quality of service (QoS) standards require that network devices, such as network switches, address these latency requirements. For example, the IEEE 802.1 standard divides network traffic into several classes of service based on sensitivity to transfer latency, and prioritizes these classes of service. The highest class of service is recommended for network control traffic, such as switch-to-switch configuration messages. The remaining classes are recommended for user traffic. The two highest user traffic classes of service are generally reserved for streaming audio and streaming video. Because the ear is more sensitive to missing data than the eye, the highest of the user traffic classes of service is used for streaming audio. The remaining lower classes of service are used for traffic that is less sensitive to transfer latency, such as electronic mail and file transfers.
Network devices such as network switches must be configured appropriately to support quality of service. In particular, the user must configure the ports and switch tables of each network switch to support the bandwidth and latency requirements of each data flow the user expects to pass through the network switch.
A stackable switch comprises a plurality of stack units. Like regular network switches, each stack unit comprises ports, a forwarding engine, and a control plane processor (CPP). But each stack unit also includes one or more stacking interfaces for interconnecting a plurality of the stack units via stacking links to form the stackable switch, in which one of the stack units is configured as the master stack unit. A stackable switch performs as a single large switch.
The resources, such as available bandwidth, of these stacking links must be considered when configuring a stackable network switch to support quality of service, thus adding to the burden of the user configuring the switch.